Seat for a chair



FIG. 1 is a perspective view of a seat for a chair, showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a side view thereof;

FIG. 5 is an opposite side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

Portions shown in broken lines form no part of the claimed design. 

CLAIM I claim, the ornamental design for a seat for a chair, as shown and described. 